This invention is concerned with an adsorption rotor whose surface layers only need to be replaced, when performance of the adsorption rotor deteriorates, or when an adsorption rotor surface layer gets clogged.
An adsorption rotor functions as either an absorber of volatile organic compounds (hereafter called “VOC”) which are then released to make them denser, or as a dehumidifier by adsorbing moisture in air, using hydrophobic zeolite, activated carbon, hydrophilic zeolite, or silica gel.
For the case of an adsorption rotor which functions as an adsorption-concentrator of VOCs, such materials as an activated carbon or a hydrophobic zeolite are used as adsorbents. Among these, a rotor using hydrophobic zeolite is nonflammable, and therefore has the advantage of avoiding a serious accident even if the VOCs adsorbed by the rotor catch fire by catalyst of the active carbon.
Moreover, both a hydrophilic zeolite and a hydrophobic zeolite have a heat resistance of more than 300° C., and adsorbed VOCs can be desorbed nearly completely by passing desorption air having a high temperature of not less than 300° C. This is helpful when VOCs having a high boiling point are adsorbed.
The adsorption rotors used for the adsorption removal of VOCs or for a dehumidifier are manufactured as shown in FIG. 1 at considerable fabrication cost, where the whole unit is made up from the separate parts of a metal aggregate boss 2, a reinforcement griddle 3, a perimeter angle 4, and a perimeter griddle 5. On the other hand, a large-sized rotor has a diameter of more than 4 m. In order to facilitate easy handling in case of transporting the rotor to the installation spot, it is divided into two or more sector pieces as shown in FIG. 2, which are then assembled at the spot. The technology about such a divided-type adsorption rotor was disclosed in JP 2004-025132. In addition, the technology about the divided-type adsorption rotor equipped with two or more adsorption blocks having the capability of suppressing crack formation in the rotor was disclosed in JP 2003-126641.
The replacement with a new adsorption rotor is required, when the rotor element deteriorates or performance of the above-mentioned adsorption rotor becomes lower due to clogging on the rotor surface by dust accumulation from operating for a long time, or paint mist being transformed to the liquid phase from the gaseous phase due to a temperature decrease when the rotor is used to adsorb paint solvents at a painting booth. The initial manufacturing cost of an integral-type rotor is comparatively cheap. However, when there is no exchange space, the rotor must be disassembled, and it will have to be exchanged with a new rotor, resulting in excessive time and effort for the exchange and thus an increase in the cost of exchange. On the other hand, the initial cost of a divided-type rotor is comparatively high. However, the sectors can be easily exchanged by removing the bolts etc. which are fixing the sector pieces, resulting in a decrease in the cost of exchange. In addition, the technology of equipping a fixed-type dust-collector was disclosed in JP 2006-090572, which aims to prevent contamination of such a rotor.
As mentioned above, in the case of the integral-type adsorption rotor shown in FIG. 1, there occurs much waste of material because rotor elements other than the deteriorated surface must be changed. Moreover, since the rotor to be exchanged is heavy, heavy industrial equipment etc. are needed during the exchange, thus increasing the replacement cost. For the case of the divided-type adsorption rotor shown in FIG. 2, it is necessary to strengthen every sector piece to be exchanged, in order to make the metal aggregate as strong as an integral-type rotor, resulting in the increase in an initial cost. In addition, whole rotor elements other than the deteriorated surface side have to be exchanged, resulting in much waste of material, similar to the case of the integral-type adsorption rotor.
For the case disclosed in JP 2006-090572, there is no capability of adsorption/desorption at the portion of a fixed-type dust-collecting filter, resulting in an easier formation of clogs than a portion of a honeycomb adsorption element, and the width of the rotor becomes wider than that for a rotor without the filter having the same performance. In other words, in the case of a honeycomb-like adsorption element, after VOCs adhere to the surface, they can be desorbed by desorption air. When VOCs adhere to the portion of the fixed mount type dust-collecting filter as disclosed in the patent document 2, it is not desorbed by desorption air, resulting in an easy formation of clogs.